blood protein amount blood interferon amount circulating IFN level blood interferon level The proportion, quantity, or volume in whole blood, serum, or plasma of proteins secreted by vertebrate cells in response to a wide variety of inducers; they confer resistance against many different viruses, inhibit proliferation of normal and malignant cells, impede multiplication of intracellular parasites, enhance macrophage and granulocyte phagocytosis, augment natural killer cell activity, and show several other immunomodulatory functions. EFO:0020486 VT:0008548 Trait.ontology EFO:0020485 circulating interferon level interferon amount